According to a post by a community manager on their Battle.net forums, Blizzard is exploring the possibility of instituting in-game micro-transaction into their massively multiplayer online game World of Warcraft. There is currently a WoW shop, but nothing in-game.

Seems that someone found a spell on the games public test servers (PTR) that would allow players to get double the experience in-game, with a reference to what looks to be an in-game store.

The response to the find on the forums was;

"We are currently exploring the possibility of adding a way for players in certain regions to make purchases directly within the game. As part of this process, elements related to this will be appearing on the PTR. We'll provide additional updates on our plans as development progresses."

Since there is no official word from Blizzard on what in-game micro-transactions would entail, it's anyone's guess at this point.